SAP Event trigger

Dear All,

I am having below requirement,any one please suggest me how can we achive .

My client is using one thrid party tool ,thrid party tool will put one .CSV file in our application server path (usr/sap/sid/interface) ,after that in our system background job needs to be run to process the file .

My doubt is how can we know the file will placed in our application server path .

Please sugegst how will trigger event in this case

Thanks